She was built in 1982 to the design of a Tango 32 cruising racing trimaran that was a semi production design from 1976 and intended for amateur and professional production by Derek Kelsall’s company Bayside Marine at Sandwich in Kent.  We believe that there were at least three boats built to this design -the prototype and two -Volantis and Trilogy, from plans and with some parts produced by Bayside Marine.  There may have been others and certainly Kelsall drew a number of designs of trimarans of about 32 feet LOA.   
However Trilogy  was built at Chertsey and after launch she was based at Canvey Island for 20 years before being sold to the South Coast and the present owners bought her in 2015.  In 2021 to 2022 the boat was professionally rebuilt and extended to update the design so that she is now 34 feet long and 24 feet wide with a draft of 1 metre and mini keels designed by Derek Kelsall on the outriggers rather than the original centre board. Volantis built in 1979 was sailed over 9000 miles from the UK to the Mediterranean and then across the Atlantic to the USA; her owners modified her based upon their experience although they were very happy with the basic Kelsall design but improved the boat by enlarging her. This was the inspiration behind the work carried out on Trilogy III albeit that we retained Derek's fin keels. Derek Kelsall very kindly supplied copies of the construction plans and these showed that he had redrawn the floats following the lessons and developments in trimaran design in 1980.
In 2025 after being moored in Southampton Trilogy III became based in Essex again but at the old port of Brightlingsea. Originally auxiliary power was an outboard, but this proved unreliable and in 2023 an inboard Nani Diesel was fitted. 
Today Trilogy III is a fast boat that sails at up to about 70% of wind speed. Her maximum speed to date is 13 knots. She is very comfortable at sea and her hulls are beautifully shaped to ride waves. She is sea kindly and seaworthy and her centre cockpit is very secure and comfortable especially with the cockpit windscreen and dodger in place, in wet and rough conditions. In fine weather the extensive deck space and the plastic trampoline netting between the hulls gives  a lot of lounging and sunbathing space. In gale force conditions she has sailed to windward with full main sail and double reefed genoa in 30 knots apparent wind and felt very safe and secure.  Large breaking waves beam on in a Solent wind over tide situation off Hurst Point, wind force 6 were taken in her stride leaving no doubts about her seaworthiness.